There are a number of diseases that can run through a flock almost imperceptibly, killing only those who already have weaknesses. If this is the case, all you can do is watch and wait. If another dies, I'd take it for a necropsy. Separate any who look suspect.
Feed can be contaminated before it ever gets to you. Botulism is rare, but aflatoxins are not. They can sneak into the feed anywhere along the line, from harvest in the fields to storage at the feed store. The lack of eggs is probably just because their systems are stressed. Keep them hydrated and give the poly-vi-sol. I know feed's not cheap, but if you're nearing the end of a bag, I'd toss it and start a new one.
I seriously doubt the ducks had anything to do with it. They've been together too long for something new to crop up.
Feed can be contaminated before it ever gets to you. Botulism is rare, but aflatoxins are not. They can sneak into the feed anywhere along the line, from harvest in the fields to storage at the feed store. The lack of eggs is probably just because their systems are stressed. Keep them hydrated and give the poly-vi-sol. I know feed's not cheap, but if you're nearing the end of a bag, I'd toss it and start a new one.
I seriously doubt the ducks had anything to do with it. They've been together too long for something new to crop up.